The present invention relates to reactors for use in electrical and electronic equipment and to a method for manufacturing the same.
As shown in FIGS. 15 and 16, a conventional reactor comprises an iron core 102 formed of laminated E-shaped electromagnetic steel plates 101, an iron core 104 formed of laminated I-shaped electromagnetic steel plates 103, and one unit of coil 105 incorporated into them, where a core gap 106 is previously defined in the E-shaped iron core 102. Two core-butting portions 107 are fixed by welding or the like. A mounting plate 110 for mounting onto other equipment is also attached to the iron core 102 by welding or the like.
Generally, the dimensions of the E- and I-shaped electromagnetic steel plates 101, 103 are of ratios as shown in FIG. 16, with a view to minimizing material loss of the electromagnetic steel plates involved in their punching process. More specifically, two sheets of the I-shaped electromagnetic steel plates 103 and a core gap portion 108 are first punched out with an H-shaped punching die, and then the rest is cut by a cut line 109. As a result, each of two sheets of the E- and I-shaped electromagnetic steel plates 101, 103 are produced at the same time. The resulting material loss of the electromagnetic steel plates is no more than the core gap portion 108.
However, such punching of the electromagnetic steel plates 101, 103 would involve a very expensive die, and therefore the type and the size of the electromagnetic steel plates 101, 103 is limited. Accordingly, when conventional E- and I-shaped electromagnetic steel plates 101, 103 are used to make a reactor, one with approximate dimensions would be chosen from among punched electromagnetic steel plates of standard dimensions prepared in some number of types. As a result, it is often the case that electromagnetic steel plates 101, 103, other than those actually desired have to be used, even though the dimensions of the electromagnetic steel plates 101, 103 are too large relative to those of the coil 105. It has therefore been difficult to attain optimum design in terms of cost for the amount of electrical wires used for the coil 105 and the amount of materials used for the iron cores 102, 104.
Furthermore, this type of reactor is, in general, often located at a place of poor cooling in the equipment to which the reactor is incorporated. Accordingly, the possible effective measures for this situation are only that the reactor would be arranged to have reduced heat generation by suppressing the reactor loss in such a way that the copper loss is reduced by increasing thickness of the wire diameter of the coil 105 or that the reactor loss is reduced by improving the material quality of the iron cores 102, 104. Thus, the reactor has confronted limitations in terms of cost and design.